I used the factory starter from the 351C. It wasn't a ton of material moved - it was mostly right around that starter. Maybe 10 sq in overall? I don't have a good pic handy.What starter did you use? And how much of the bellhousing did you have to remove to clear the starter? Would like to do a swap in a 67 XR7 one day... Currently has a 4R70W
You'll like the 6R80 swap. It's still going strong.